A conventional rotary electric machine that is applied to a railway vehicle is rotated in a normal direction and a reverse direction with equal frequency because a railway vehicle moves in a forward direction and a rearward direction with equal frequency. Therefore, an internal fan or an external fan used in the rotary electric machine uses a flat blade or a blade in which a straight line and an arch are combined (for example, Patent Literature 1 mentioned below).
Meanwhile, a conventional rotary electric machine that is applied to a railway vehicle is required to further enhance cooling efficiency by increasing an air flow amount in a fan, while achieving reduction in its size. However, because noise generated from the fan increases in proportion to the cooling efficiency (that is, the air flow amount), there is a case where the noise level cannot satisfy a required noise value. Therefore, the conventional rotary electric machine employs a method of selecting a fan that generates a reduced amount of air flow such that a noise value falls within a required range while cooling efficiency is decreased.
However, when the rotary electric machine is designed by this method, a fan with low cooling efficiency is selected, and therefore a heat amount generated from the rotary electric machine needs to be decreased. In order to decrease this heat amount, for example, it is a common procedure to increase an amount of copper in a rotor bar provided in a rotor, to thereby decrease a resistance. However, the common procedure inevitably increases the size of the rotary electric machine. As described above, when the value of noise generated from the fan is high, the air flow amount has to be decreased, and when the air flow amount is decreased, cooling efficiency is reduced. Accordingly, the heat generation amount itself in the rotary electric machine needs to be decreased. As a result, there is a problem that the size of the rotary electric machine has to be increased. Therefore, further improvements of the fan have been desired.